Electrode for electrostatic filters



Feb. 26, 1952 F. LANDGRAF ELECTRODE FOR ELECTROSTATIC FILTERS FiledApril 16 1951 f E 4 E 5 INVENTOR. George E Landgraf LAM/7am 301M H/SATTORNEYS Patented Feb. 26, 1952 ELECTRODE FOR ELECTROSTATIC FILTERSGeorge F. Landgraf, Pittsburgh, Pa., assignor to Trion, Inc., McKeesRocks, Pa., a corporation of Pennsylvania Application April 16, 1951,Serial No. 221,261

Claims.

This application relates to improvements in electrodes for electrostaticfilters and particularly to electrodes in electrostatic filters forcleaning air in buildings or homes, which filters employ a thin wire asone of the electrodes for ionizing particles in the air prior tocollecting the particles on charged plates. Electrostatic air filtersgenerally comprise two sections or units, first an ionizing unit andsecond a collecting unit. The ionizing unit comprises a plurality ofWires spaced parallel to each other and across the air inlet passage ofthe filter. The wires are charged at a high potential. Oppositelycharged members are spaced between the wires. These members may beextensions of some of the collectin plates of the collecting unit orseparately mounted tubes. The collecting unit comprises a series ofparallel plates spaced from each other with opposite charges on adjacentplates. Air enters the intake of the filter and first passes through theionizing unit where particles carried in the air are ionized. The airthen passes through the collecting unit and the ionized particles arecollected by oppositely charged plates of the collecting unit,

Such electrostatic air filters howl in dry weather and at a pitch whichis very annoying to occupants of a house or building. It has been foundthat the howl is caused by vibration of the ionizing wires of the airfilter and various attempts have been made to remedy this defect butwithout success. For example, it has been proposed to rigidly supportthe ionizing wires at their center points in addition to their ends.This did not prevent the howl; in fact it made the howl worse becauseeach half length of the wire vibrated and thus the pitch of the howl wasraised an octave. The rigid supports also created a dead space in theionizing unit past which air could flow without being ionized.

As will appear hereinafter, I have invented an ionizing wire electrodehaving means thereon to reduce the lateral vibration of the wire andthereby reduce, if not completely eliminate, the objectionable hum orhowl above referred to. My electrode comprises a wire which i similar toionizing wires heretofore used but which has in addition at least twobeads which are threaded onto the wire and held in position adjacent thecentral portion of the wire when it is mounted in operative position inan air filter. One bead is firmly secured to the wire so that it cannotmove relative to the wire. A second bead has a hole extending through itand through which the wire passes. The diameter of thi hole is larger 2than the diameter of the ionizing wire so that the bead can movelaterally on the wire. When the wire is mounted in the filter, theloosely threaded bead rests on and is supported by the bead which hasbeen firmly secured to the wire.

If the wire vibrates laterally during operation of the filter, it willcarry with it the bead which is firmly held to the wire but not theloose bead, unless the amplitude of the vibration is greater than thedifference between the diameter of the hole in the bead and the diameterof the wire. Upon vibration of the wire, therefore, a sliding frictionwill be developed between the contacting surfaces of the two beads. Ihave found that this friction will absorb the energy of vibration of thewire and thereby damp out the vibration and reduce the tendency of theair filter to howl.

In the accompanying drawings, I have illustrated a present preferredembodiment of my invention, in which- Figure 1 is a front elevation ofan ionizing unit of an electrostatic air filter;

Figure 2 is a rear view of the ionizing unit shown in Figure 1;

Figure 3 is an elevation view of an ionizing wire embodying'myinvention; and

Figure 4 is a central vertical section through the ionizing wire shownin Figure '3.

Figure 1 shows an ionizing unit of an electrostatic filter havingelectrodes which embody my invention mounted therein. The ionizing unitis more fully described in my copending application Serial No. 138,355filed January 13, 1950. The unit comprises a rectangular frame 5 havinga rectangular opening therein with side flanges 6 and 1 extendinginwardlly from the sides of the rectangular opening. A top flange 8 anda bottom flange 8a extend inwardly from the top and bottom edges of theopening and support tubes 9 which act as one set of electrodes in theionizing unit. Brackets l0 and II are mounted on insulators (not shown)extending from the rear side of the rectangular frame 5 and supportionizing wires l2 which constitute the other set of electrodes in theunit.

Figures 3 and 4 show my electrode on a scale larger than the scale usedin Figures 1 and 2. The electrode comprises a suitable length of veryfine wire of the type heretofore used in electrostatic filters. The wirehas loops 13 at each end to facilitate its mounting in the filter. Itcan be secured, for example, to the brackets Ill and .II shown in Figure2. The wire also has beads I4, l5 and I6 adjacent its central portion,the beads being made of lead or other heavy material. Al=

so, as shown in Figure 4 the beads I4 and I6 are secured to the wire l2.This may be done by pressing the beads onto the wire or by affixing themto the wire by a suitable glue or adhesive or by holder. The bead [5 hasa centrally positioned hole [I which extends through the bead andthrough which the wire I2 is threaded. ihe diameter of the hole I! isconsiderably greater than the diameter of the wire l2 so that the beadis very loosely threaded onto the wire.

As shown in Figures 1 and 2 the wires are mounted in the electrostaticair filter so that they extend vertically. When they are thus mounted,the bead l5 rests on either the bead I l or the bead l5 depending uponhow the wire has'been placed in the filter, two beads M and I6 beingprovided on each wire on either of the bead 15 so that either end of thewire can be fastened to the top supporting bracket 19.

I have found that ionizing wires that are constructed as described justabove will not vibrate laterally sufiiciently to. create howl when theyare in use in an electrostatic air filter. The vibration is damped byreason of frictional engagement of the bead I5 with either the bead I4or 15 whichever happens to be supporting the bead when the wire isinstalled in the filter. When a wire l2 begins to vibrate it carrieswith it the bead 14 but not the bead l5 since the diameter of the holeI? in the bead i5 is considerably larger than the diameter of the wire.Ihis develops friction between the adjacent surfaces of the bead M (orIE) and the bead I5. This friction absorbs the energy of vibration ofthe wire and thereby clamps the vibration sufficiently to prevent theelectrostatic air filter from howling.

While I have described a present preferred embodiment of my invention,it is to be understood that it may be otherwise embodied within thescope of the following claims.

I claim:

1. An electrode for electrostatic filters comprising a wire adapted tobe supported at its ends in the filter and two beads on the wire, onebead being secured to the wire adjacent the central portion of the wire,the other bead being loosely mounted on the wire and supported by thefirst mentioned bead when the wire is in position in the filter.

2. An electrode for electrostatic filters comprising a wire adapted tobe supported at its ends in the filter and two beads on the wire, onebead being secured to the wire adjacent the central portion of the wire,the other bead having a hole extending through the bead, said holehaving a diameter larger than the diameter of the wire, said second beadbeing supported in position on the wire by said first bead when the wireis in position in the filter.

3. An electrode for electrostatic filters comprising a wire adapted tobe supported at its ends in the filter and three beads on the wire, twoof said beads being seecured to the wire adjacent its central portion,but spaced from each other, the third bead being loosely mounted on thewire between said first two beads, whereby said third bead is supportedon the wire by one of said beads which are secured to the wire when thewire is in operative position in the filter.

4. In an electrostatic filter having an ionizing wire, means for dampinglateral vibration of the wire, said means comprising a bead secured tothe wire adjacent its central portion, and a second bead loosely mountedon the wire and adapted to be supported by said first bead when the wireis mounted inoperative position in the filter.

5. In an electrostatic filter having an ionizing wire, means for dampinglateral vibration of the wire, said means comprising a bead secured tothe wire adjacent its central portion, and a second bead having a holetherethrough, the ionizing wire being threaded through said hole, thediameter of the hole being larger than the diameter of the wire wherebysaid second bead is supported on the wire by said first bead when thewire is mounted in operative position in the filter.

GEORGE F. LANDGRAF.

REFERENCES CITED The following references are of record in the file ofthis patent:

FOREIGN PATENTS

